Process for fabricating RuSixOy-containing adhesion layers

ABSTRACT

A method for use in the fabrication of integrated circuits includes providing a substrate assembly having a surface. An adhesion layer is formed over at least a portion of the surface. The adhesion layer is formed of RuSi x O y , where x and y are in the range of about 0.01 to about 10. The adhesion layer may be formed by depositing RuSi x O y  by chemical vapor deposition, atomic layer deposition, or physical vapor deposition or the adhesion layer may be formed by forming a layer of ruthenium or ruthenium oxide over a silicon-containing region and performing an anneal to form RuSi x O y  from the layer of ruthenium and silicon from the adjacent silicon-containing region. Capacitor electrodes, interconnects or other structures may be formed with such an adhesion layer. Semiconductor structures and devices can be formed to include adhesion layers formed of RuSi x O y .

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a divisional of application Ser. No.09/651,859, filed Aug. 30, 2000, pending.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to semiconductor devices and thefabrication thereof. More particularly, the present invention pertainsto RuSi_(x)O_(y)-containing adhesion layers, structures incorporatingsuch adhesion layers, and methods of fabricating the same.

[0004] 2. State of the Art

[0005] Integrated circuits typically include various conductive layers.For example, in the fabrication of semiconductor devices, such asdynamic random access memories (DRAMs) and static random access memories(SRAMs), conductive materials (e.g., electrode materials such as Pt andRu) are typically expected to be used in the formation of storage cellcapacitors and interconnection structures (e.g., conductive layers incontact holes, vias, etc.). In integrated circuits, conductive materialsmay require some sort of adhesion layer in order to prevent delaminationof the films. In forming such integrated circuit structures, theadhesion layer must be able to withstand the various anneals performedon the capacitor electrode and dielectric. The adhesion of grown anddeposited films used in semiconductor processing must be excellent bothas deposited and after subsequent processing. If films lift from thesubstrate device, failure can result, leading to potential reliabilityproblems. For example, failure of the adhesive can result in fracture ofthe mechanical bond (e.g., die separation) or failure of the circuit bydegradation (e.g., contamination or loss of thermal or electricalproperties) and could preclude the use of the desired film.

[0006] Use of various adhesive layers is known in the art. For example,in silicon devices having small diameter contact holes and tungstenfilling the contact holes, tungsten is typically used as a contact fillmaterial, which requires the use of an underlying contact layer as wellas an underlying adhesion layer. The contact layer is needed to provideboth good ohmic contact to the silicon device, and also serves as anadhesion layer between the tungsten fill and the sides of a siliconoxide contact hole. Titanium is usually used for this purpose, providinggood ohmic contact, after centering converts titanium to titaniumdisilicide at the bottom of the contact hole. However, where only atitanium adhesive layer is used, the subsequent tungsten chemical vapordeposition process severely damages the exposed titanium. The tungstendeposition is performed via the decomposition of tungsten hexafluoride,and in addition to the deposition of tungsten, a serious reaction withtitanium occurs, eroding the critical contact and adhesive layer. Toovercome the titanium erosion phenomena, an adhesion layer of eithersputtered tungsten or titanium nitride on the titanium layer has beensuggested. For example, U.S. Pat. No. 5,286,675 describes a process inwhich a titanium-titanium nitride composite is used in contact holesprior to filling with tungsten. However, that process does notsufficiently eliminate the attack of titanium, particularly where poortitanium nitride coverage exists. The lack of adequate titanium nitridecoverage leads to erosion of the underlying titanium adhesive layerduring the subsequent tungsten deposition process, resulting in a lackof tungsten adhesion, which is described as “tungsten peeling” or the“volcano effect.”

[0007] Adhesion layers have also been employed for providing adhesionbetween a substrate and overlying seed layers in metallization areas ofsubstrates. For example, U.S. Pat. No. 5,126,016 provides a chromiumadhesion layer for thin-film microelectronic circuitry. However, themetallization of high aspect ratio thin-film structures cause highstress which may lead to adhesions failure, as described above.

[0008] Various metals and metallic compounds (e.g., metals such asplatinum and conductive metal oxides such as ruthenium oxide) have beenproposed for use as electrodes or as electrode stack layers with highdielectric constant materials. However, such electrical connections mustbe constructed so as to not diminish the beneficial properties of thehigh-dielectric constant materials. For example, in order for platinumor ruthenium oxide to function well as a bottom electrode or as one ofthe layers of an electrode stack, an oxidation-resistant barrier layerand adhesive layer are typically required. These layers, either as acombined layer or as individual layers, must provide adhesion between asubstrate and deposited layers and prevent oxidation of silicon locatedat the surface of the electrode stack during the oxygen anneal of thehigh dielectric constant materials (e.g., Ta₂O₅ or BaSrTiO₃), whichoxidation can result in a decreased series capacitance and, in turn,degradation of the storage capacity of the cell capacitor. Similarly, O₂diffusing through the platinum or RuO₂ to the underlying Si yields SiO₂at the base of the electrode, thus decreasing series capacitance.Platinum and ruthenium oxide, when used alone as an electrode andadhered to, are generally too permeable to oxygen and silicon to be usedas a bottom electrode of a storage cell capacitor formed on a siliconsubstrate region.

[0009] In view of the aforementioned shortcomings of the methods andstructures being currently practiced, it would be advantageous toprovide an adhesion layer that prevents delamination of deposited filmscontacting the same, withstands the various anneals performed on thecapacitor electrode and dielectric, maintains the performance of highdielectric capacitors, prevents oxidation of underlying Si contacts, andprevents Si diffusion into an electrode or dielectric. It would be offurther advantage to form an adhesion layer that can survive a tape testboth as deposited and after an annealing step and that reduces oreliminates the diffusion or migration of ruthenium into an elemental Sior a silicide layer, or vice versa, which typically occurs as a resultof the high solubility of silicon in ruthenium.

BRIEF SUMMARY OF THE INVENTION

[0010] The present invention provides RuS_(x)O_(y)-containing adhesionlayers, along with structures incorporating such adhesion layers andmethods of fabricating the same.

[0011] A method of fabricating semiconductor devices and assemblies(e.g., integrated circuits) according to the present invention includesproviding a substrate assembly having a surface. An adhesion layer isformed over at least a portion of the surface. The adhesion layerincludes RuSi_(x)O_(y), where x and y are in the range of about 0.01 toabout 10. The adhesion layer may, additionally, include Ru and/orRuSi_(x). In one particular embodiment of the method, the adhesion layeris formed of RuSi_(x)O_(y), where x is in the range of about 0.1 toabout 3, and more preferably is about 0.4, and where y is in the rangeof about 0.01 to about 0.1, and more preferably is about 0.05.

[0012] In another embodiment of the method, the adhesion layer is formedby depositing a mixed film of Ru—RuSi_(x)—RuSi_(x)O_(y) by chemicalvapor deposition (CVD). In yet another embodiment of the method, theadhesion layer is formed by CVD deposition of Ru—RuSi_(x)O_(y)in anoxidizing atmosphere, such as O₂, N₂O, O₃, or any other suitableinorganic or organic oxidizer. All of the foregoing adhesion layers mayalso be formed by atomic layer deposition. This process can result inthe formation of multiple (preferably up to 300)RuSi_(x)O_(y)-containing diffusion adhesion monolayers and, morepreferably, formation of from three to five monolayers ofRuSi_(x)O_(y)-containing adhesion layers.

[0013] In an alternative embodiment, the adhesion layer is formed byphysical vapor deposition (PVD) of the adhesion layers of the presentinvention. In one particular embodiment of the PVD deposition method,mixed films of Ru—RuSi_(x)—RuSi_(x)O_(y) are deposited to form anadhesion layer. Alternatively, mixed films of Ru—RuSi_(x)O_(y) may bedeposited to form an adhesion layer.

[0014] According to yet another method of the present invention, acapacitor is formed by providing a silicon-containing region of asubstrate assembly. A first electrode is then formed on at least aportion of the silicon-containing region of the substrate assembly. Thefirst electrode includes an adhesion layer having RuSi_(x)O_(y), where xand y are in the range of about 0.01 to about 10. A high dielectricmaterial is then formed over at least a portion of the first electrodeand a second electrode is provided over the high dielectric material.The second electrode may also include an adhesion layer havingRuSi_(x)O_(y), where x and y are in the range of about 0.01 to about 10.

[0015] In an alternative embodiment of the method, one or moreconductive layers are formed relative to the RuSi_(x)O_(y)-containingadhesion layer. The one or more conductive layers are formed of at leastone of a metal or a conductive metal oxide, e.g., formed from materialsselected from the group of RuO₂, RhO₂, MoO₂, IrO₂, Sr RuO₃, Ru, Rh, Pd,Pt, and Ir.

[0016] A semiconductor device structure according to the presentinvention includes a substrate assembly including a surface and anadhesion layer over at least a portion of the surface. The adhesionlayer is formed of RuSi_(x)O_(y), where x and y are in the range ofabout 0.01 to about 10.

[0017] In one embodiment of the structure, at least a portion of thesurface is a silicon-containing surface and the structure includes oneor more additional conductive layers over the adhesion layer formed ofat least one of a metal and a conductive metal oxide, e.g., formed frommaterials selected from the group of RuO₂, RhO₂, MoO₂, IrO₂, Ru, Rh, Pd,Pt, and Ir.

[0018] Semiconductor assemblies and structures according to the presentinvention are also described. One embodiment of such a structureincludes a capacitor structure having a first electrode, a highdielectric material on at least a portion of the first electrode, and asecond electrode on the dielectric material. At least one of the firstand second electrodes includes an adhesion layer formed ofRuSi_(x)O_(y), where x and y are in the range of about 0.01 to about 10.

[0019] Another such structure is an integrated circuit including asubstrate assembly including at least one active device and asilicon-containing region. An interconnect is formed relative to the atleast one active device and the silicon-containing region. Theinterconnect includes an adhesion layer on at least a portion of thesilicon-containing region. The adhesion layer is formed ofRuSi_(x)O_(y), where x and y are in the range of about 0.01 to about 10.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0020] The present invention will be better understood from reading thefollowing detailed description taken in conjunction with theaccompanying drawings, wherein:

[0021]FIG. 1 shows a device structure including aRuSi_(x)O_(y)-containing adhesion layer according to the presentinvention;

[0022] FIGS. 2-4 show one method of forming the RuSi_(x)O_(y)-containingadhesion layer according to the present invention;

[0023]FIG. 5 shows a structure including a RuSi_(x)O_(y)-containingadhesion layer according to the present invention as part of a multipleconductive layer stack;

[0024]FIG. 6 is a structure showing a high dielectric capacitorincluding an electrode having a RuSi_(x)O_(y)-containing adhesion layeraccording to the present invention;

[0025]FIG. 7 illustrates the use of a RuSi_(x)O_(y)-containing adhesionlayer in a storage cell capacitor application; and

[0026]FIG. 8 illustrates the use of a RuSi_(x)O_(y)-containing adhesionlayer in a contact application.

DETAILED DESCRIPTION OF THE INVENTION

[0027] Referring to FIG. 1, a structure 20 according to the presentinvention includes a substrate assembly 21 and aRuSi_(x)O_(y)-containing adhesion layer 23 disposed on a surface 22 ofthe substrate assembly 21, e.g., a silicon-containing substrate. Thestructure 20 further includes a conductive layer 24. As used herein,“substrate assembly” refers to either a semiconductor substrate such asthe base semiconductor layer (e.g., base silicon layer of a wafer), asilicon layer deposited on another material (e.g., silicon on sapphire),or a semiconductor substrate having one or more layers, structures,and/or regions formed thereon or therein. It is understood thatreference to a substrate assembly herein also includes any known processsteps that may have been previously used to form or define regions,junctions, various structures or features, and openings (e.g., vias,contact openings, high aspect ratio openings, etc.).

[0028] The structure 20 is representative of a RuSi_(x)O_(y)-containingadhesion layer that may be used for any application requiring aneffective adhesion layer, for example, to adhere two adjacent layerstogether, prevent delamination of films in a semiconductor structure,and to prevent oxidation of an underlying Si contact. TheRuSi_(x)O_(y)-containing adhesion layer 23 may be used in thefabrication of semiconductor devices or assemblies where it is necessaryor desirable to enhance or ensure adhesion of one material to anadjacent material. As described more fully hereinafter, theRuSi_(x)O_(y)-containing adhesion layer 23 may include Ru and/orRuSi_(x), in addition to RuSi_(x)O_(y).

[0029] The substrate assembly 21 may, for example, be representative ofa contact structure having an opening extending to a silicon-containingsurface. In such a structure, adhesion layers are commonly used withinthe contact opening to prevent undesirable reactions, such as reactionsbetween the conductive contact material and the silicon-containingsurface that lead to erosion of one or both such layers and a generallack of adhesion between the contact and silicon-containing materials.By way of example, the RuSi_(x)O_(y)-containing adhesion layer 23 may beinterposed between other layers of materials (e.g., ruthenium oxide,platinum, etc.) forming an electrode of a capacitor.

[0030] It is understood that persons having ordinary skill in the artwill recognize that the adhesion layers of the present invention can beused in any semiconductor processes, structures, assemblies and devices(e.g., CMOS devices and memory devices) which utilize adhesion layers.

[0031] The amount of elemental Si and SiO₂ incorporated into theRuSi_(x)O_(y)-containing adhesion layer 23 is sufficient to accomplishadhesion and oxidation resistance in between one or more layers ofmaterials in semiconductor devices. Preferably, theRuSi_(x)O_(y)-containing adhesion layer 23 includes an atomiccomposition such that x and y are in the range of about 0.01 to about10. More preferably, x and y are in the range of about 1 to about 3, andyet more preferably, x is about 0.4 and y is about 0.05. Likewise, inembodiments of the invention where the RuSi_(x)O_(y)-containing adhesionlayer 23 of the present invention contains RuSi_(x), the RuSi_(x)includes an atomic composition such that x is in the range of about 0.01to about 10, and more preferably in the range of about 0.1 to about 0.5,and yet more preferably, x is about 0.4.

[0032] The thickness of the RuSi_(x)O_(y)-containing adhesion layer 23is dependent upon the application for which it is used. Preferably, thethickness is in the range of about 10 Å to 1,000 Å. More preferably, thethickness of the RuSi_(x)O_(y)-containing adhesion layer 23 is in therange of about 50 Å to about 500 Å. For example, this preferredthickness range of about 50 Å to about 500 Å is applicable to aRuSi_(x)O_(y)-containing adhesion layer used for forming a bottomelectrode stack of a capacitor structure.

[0033] The conductive layer 24 shown in FIG. 1 is representative of oneor more layers. For example, the conductive layer 24 may include one ormore layers formed of a metal or metal oxide, or combinations thereof.Such layers may include one of RuO₂, MoO₂, Rh, RhO₂, IrO₂, Ru, Pt, Pdand Ir, such as when the RuSi_(x)O_(y)-containing adhesion layer is usedin an electrode stack. Alternatively, the conductive layer 24 may be acontact material, such as aluminum, when the RuSi_(x)O_(y)-containingadhesion layer is used in a contact or interconnect application. Suchconductive layers may be formed by any method known to those skilled inthe art.

[0034] The RuSi_(x)O_(y)-containing adhesion layer 23 may be formed byvarious processes. For example, the formation of theRuSi_(x)O_(y)-containing adhesion layer may be sputter deposited from adeposition target of RuSi_(x)O_(y), may be deposited by the sputteringfrom a deposition target of ruthenium onto a silicon-containing surfacefollowed by an anneal, may be deposited by physical vapor deposition(PVD) of Ru—RuSi_(x)—Ru_(x)O_(y) mixed films, may be deposited by CVDusing a ruthenium precursor and a silicon precursor in an oxidizingatmosphere, or may be deposited by CVD of Ru—RuSi_(x)—RuSi_(x)O_(y)films. Suitable CVD processes include, for example, atmospheric pressurechemical vapor deposition (APCVD), low pressure chemical vapordeposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD),or any other known chemical vapor deposition technique. Further, theRuSi_(x)O_(y)-containing adhesion layer may be formed by depositing alayer of ruthenium using CVD onto a silicon-containing surface followedby an annealing process.

[0035] The aforementioned CVD processes may be carried out in a chemicalvapor deposition reactor, such as a reaction chamber available under thetrade designation of 7000 from Genus, Inc. (Sunnyvale, Calif.), areaction chamber available under the trade designation of 5000 fromApplied Materials, Inc. (Santa Clara, Calif.), or a reaction chamberavailable under the trade designation of Prism from Novelus, Inc. (SanJose, Calif.). However, any reaction chamber suitable for performing CVDmay be used.

[0036] Oxidizing agents for use in the CVD process may be any gaseousreactant which is capable of reacting with the Ru precursor compounds atthe decomposition temperatures of the latter to formRu—RuSi_(x)—RuSi_(x)O_(y) films. Suitable oxidizing agents for use withthe present method include, but are not limited to, air, oxygen, andoxygen-containing compounds, such as nitrous oxide, tetrahydrofuran, andcarbon dioxide, and are preferably selected from mildly oxidizinggaseous oxygen sources.

[0037] CVD may be defined as the formation of a nonvolatile, solid filmon a substrate by the reaction of vapor phase reactants, i.e., reactantgases, that contain desired components. The reactant gases areintroduced into the reaction chamber. The gases decompose and react at aheated wafer or other semiconductor substrate surface to form thedesired layer. Chemical vapor deposition is just one process ofproviding thin layers on semiconductor wafers, such as films ofelemental metals or compounds (e.g., platinum, ruthenium oxide, iridium,molybdenum oxide, etc). Chemical vapor deposition processes are favoredin many respects because of the process capability to provide highlyconformal layers even within deep contacts and other openings. Thus, asdescribed further below with reference to FIGS. 5 and 6, CVD processingis preferably used to provide highly conformal layers within deepcontacts and other openings such as for lower electrodes of storage cellcapacitors. It will be readily apparent to one skilled in the art thatalthough CVD is the preferred process, that the CVD process may beenhanced by various related techniques such as plasma assistance, photoassistance, laser assistance, as well as other techniques. In addition,atomic layer deposition could be used to form conformal layers. This isa variant of CVD in which a single atomic layer is formed on thesurface. The layer thickness is self limiting to ≦1 atomic layer. Thislayer is exposed to reaction gas after pump down or purge, is fullyreacted, and the reaction gas pumped away. The process is repeated toyield the desired number of layers.

[0038] In addition, atomic layer deposition could be used to form thelayer. This process is a special type of CVD in which, based on theprocess conditions and/or chemistry used, at most, a single layercomprising a single type of organometallic precursor is deposited at onetime. Accordingly, the thickness of the layer is, at most, the thicknessof the relevant adsorbed species, at which point no more precursor willadsorb; hence, the layer may be referred to as a “monolayer.” Once onemonolayer is deposited, the deposition gas is purged and a secondreaction gas is introduced to react with the first monolayer to producethe desired compound and activate the surface for the next step.Additional monolayers may be provided in a similar manner, provided thegases from earlier deposition steps are purged from the chamber beforeeach subsequent monolayer is deposited.

[0039] One preferred method of forming the RuSi_(x)O_(y)-containingadhesion layer 23 is by depositing RuSi_(x) by CVD. The CVD process isconducted with a ruthenium precursor being delivered to a reactionchamber along with a silicon precursor. Typical ruthenium precursors inuse include liquid ruthenium metal-organic precursors. The rutheniumprecursor is contained in a bubbler reservoir through which a carriergas, such as helium or any other inert gas, i.e., a gas that isnonreactive with other gases of the process (e.g., nitrogen, argon,neon, and xenon), is bubbled through the reservoir containing theprecursor to deliver the precursor to the reaction chamber. For example,a carrier gas having a volumetric flow rate in the range of about onesccm to about 500 sccm may be used in a bubbler having a pressure in therange of about 0.5 torr to about 50 torr and a temperature in the rangeof about 30° C. to about 70° C. to deliver a ruthenium precursor to thereaction chamber.

[0040] Any ruthenium containing precursor may be used in accordance withthe present invention. Preferably, the ruthenium precursors are liquidruthenium complexes of the following formula (Formula I): (diene)Ru(CO)₃wherein: “diene” refers to linear, branched, or cyclic dienes, bicyclicdienes, tricyclic dienes, fluorinated derivatives thereof, combinationsthereof, and derivatives thereof additionally containing heteroatomssuch as halide, Si, S, Se, P, As, or N. These precursor complexes andothers, as well as various CVD processes, are described in Assignees'copending patent application U.S. Ser. No. 09/141,236, entitled“Precursor Chemistries for Chemical Vapor Deposition of Ruthenium andRuthenium Oxide,” and in Assignees' copending patent applicationentitled “Methods for Preparing Ruthenium and Osmium Compounds” havingU.S. Ser. No. 09/141,431, both of which are incorporated by referenceherein. Additional precursors and methods of depositing ruthenium layersare generally discussed in U.S. Pat. No. 5,372,849 to McCormick et al.,which is incorporated by reference herein. More preferably, theruthenium precursors used according to the present invention include oneof C₆H₈Ru(CO)₃, (C₇H₁₀)Ru(CO)₃, bis(cyclopentadienyl) ruthenium (II),triruthenium dodecacarbonyl, and cyclopentadienyl dicarbonyl ruthenium(II) dimer.

[0041] The silicon precursor is also provided to the reaction chamber.For example, the silicon precursor may include a silicon hydride orsilane such as dichlorosilane (DCS, SiH₂Cl₂), silane (SiH₄), disilane(H₃SiSiH₃), trichlorosilane (TCS, SiHCl₃), or any other siliconprecursor as would be recognized by one skilled in the art. For example,the silicon precursor may be provided to the reaction chamber at a ratein the range of about 0.1 sccm to about 500 sccm. Preferably, the rateis about 10 sccm.

[0042] One skilled in the art will recognize that the manner in whichthe gases are introduced into the reaction chamber may include one ofvarious techniques. For example, in addition to provision by bubblertechniques, the introduction may be accomplished with the use ofcompounds which are gases at room temperature or by heating a volatilecompound and delivering the volatile compound to the reaction chamberusing a carrier gas. Further, solid precursors and various methods ofvaporizing such solid precursors may also be used for introduction ofreactant compounds into the chamber. As such, the present invention isnot limited to any particular technique. For example, reactant gases canbe admitted at separate inlet ports. In addition to the other gasesprovided to the reaction chamber, an optional carrier or dilution gas(i.e., a gas that is nonreactive with the reactant gases) may also beintroduced into the chamber such as to change the concentrations of thegases therein. For example, argon gas may be introduced into the chamberat a varied flow rate. Oxidizing gases can also be introduced into thereaction chamber when an oxidizing atmosphere is desired.

[0043] In accordance with one method of forming theRuSi_(x)O_(y)-containing adhesion layer, the ruthenium precursor gas,the silicon precursor gas, optionally a dilution gas, and an oxidizinggas (if necessary) is provided to the reaction chamber. In thispreferred CVD process, the reaction chamber pressure is preferablymaintained at a deposition pressure of about 0.1 torr to about 10 torr.The deposition temperature at the wafer surface upon which theRuSi_(x)O_(y) adhesion layer 23 is deposited is preferably held at atemperature in a range of about 100° C. to about 700° C., morepreferably in the range of about 200° C. to about 500° C.

[0044] Another preferred method of forming a RuSi_(x)O_(y)-containingadhesion layer 29 according to the present invention is shown in FIGS.2-4. This method forms the RuSi_(x)O_(y)-containing adhesion layer 29 bydepositing a layer of ruthenium 28, as shown in FIG. 2, onto asilicon-containing region of substrate assembly 26 using a CVDtechnique. Generally, the method can be carried out by introducing aruthenium precursor composition into a CVD chamber together with acarrier or dilution gas, as described in Applicant's Assignees'copending patent application entitled “Methods for Preparing RutheniumOxide Films,” having Ser. No. 09/140,932, the disclosure of which isincorporated by reference herein. This ruthenium deposition step isfollowed by an annealing process to react the silicon-containing regionhaving silicon-containing surface 27 with the ruthenium layer 28. Theannealing process is carried out in an oxidizing atmosphere, such asoxygen gas, to further oxidize the deposited layer and to form theRuSi_(x)O_(y)-containing adhesion layer 29 shown in FIG. 3. Variouscombinations of carrier gases and/or reaction (oxidizing) gases can beused in the methods of the present invention. The gases can beintroduced into the CVD deposition chamber in a variety of manners, suchas directly into a vaporization chamber of the CVD deposition chamber orin combination with the ruthenium precursor composition. Thereafter, aconductive layer 31 (e.g., the conductive layer 24 of FIG. 1) is formedon the RuSi_(x)O_(y)-containing adhesion layer 29, as shown in FIG. 4.

[0045] The annealing process is preferably performed in situ in thereaction chamber in a nitrogen atmosphere, although any othernonreactive atmosphere may be used, e.g., argon. Preferably, theannealing temperature is within the range of about 400° C. to about1000° C., more preferably about 500° C. The anneal is preferablyperformed for a time period of about 0.5 minutes to about 60 minutes.One of ordinary skill in the art will recognize that such temperaturesand time periods may vary and that the anneal parameters should besufficient to convert the ruthenium layer 28, following oxidation, intoRuSi_(x)O_(y) 29, where x and y are in the ranges previously describedherein. For example, various anneal techniques (e.g., furnace anneals,anneal, process RTP, and rapid thermal smearing) may be used and may beperformed in one or more annealing steps. Likewise, it may not benecessary or desirable to convert the entire ruthenium layer toRuSi_(x)O_(y) as long as sufficient adhesion properties are attainedwith the amount of ruthenium converted.

[0046] The ruthenium layer 28 deposited for forming theRuSi_(x)O_(y)-containing adhesion layer 29 is preferably of a thicknessin the range of about 10 Å to about 1000 Å. More preferably, thethickness is in the range is about 50 Å to about of 500 Å, and even morepreferably, the thickness is about 300 Å.

[0047] Referring to FIG. 5, a structure 30 is shown which includes asubstrate assembly 32 (e.g., a silicon substrate region) and a stack 34.The stack 34 includes conductive layers 41-44. One or more of theconductive layers 41-44 may be RuSi_(x)O_(y)-containing adhesion layersaccording to the present invention. The one or more conductive layers,in addition to including one or more RuSi_(x)O_(y)-containing adhesionlayers, may include conductive layers formed of various conductivematerials. For example, the conductive layers may include, but are notlimited to, layers formed of metals, metal oxides or combinationsthereof. By way of example, the conductive layers may include metalssuch as rhodium, palladium, ruthenium, platinum, and iridium or metaloxides such as ruthenium oxide, rhodium oxide, molybdenum oxide andiridium oxide.

[0048] The stack 34 may be used for various applications, such asinterconnection applications and capacitor applications. For example,the stack 34 may be used as an electrode for a storage cell capacitorwith the substrate assembly 32 including a silicon-containing surface33. In accordance with the present invention, the layer 41 may be formedas the RuSi_(x)O_(y)-containing adhesion layer to adhere or enhanceadhesion (prevent delamination) between layer 42 and substrate assembly32 and to also prevent oxygen diffusion to the silicon-containingsurface 33 of substrate assembly 32.

[0049]FIG. 6 shows a structure 50 including substrate assembly 52 (e.g.,a silicon substrate) and capacitor structure 54 formed relative thereto.Capacitor structure 54 includes a first electrode 56, a second electrode60, and a high dielectric constant layer 58 interposed therebetween. Thedielectric layer may be of any suitable material having a desirabledielectric constant, such as, for example, Ba_(x)Sr_((1-x))TiO₃ [BST],BaTiO₃, SrTiO₃, PbTiO₃, Pb(Zr,Ti)O₃ [PZT], (Pb,La)(Zr,Ti)O₃ [PLZT],(Pb,La)TiO₃ [PLT], Ta₂O₅, KNO₃, and/or LiNbO₃. With use of the highdielectric constant layer 58, adhesion properties between theaforementioned layers and resistance to oxidation in the underlyingsubstrate assembly 52 and/or portions of the capacitor structure 54 areparticularly important.

[0050] In a bottom electrode of a capacitor structure, such as thatshown in FIG. 6, the electrode layer or electrode stack must besufficiently adhered to prevent delamination during various processsteps (e.g., anneal process), particularly due to the high temperatureprocesses used to form the high dielectric constant materials, and toalso act as an effective oxidation barrier to the underlying siliconsubstrate. Such properties are particularly essential when the substrateassembly 52 includes a silicon-containing surface 53 (e.g., polysilicon,silicon substrate material, N-doped silicon, P-doped silicon) upon whichthe capacitor is formed, due to oxidation of the diffused silicon whichmay result in degraded capacitance, such as that seen in memory devices.Additionally, the electrode stack must act as an oxygen barrier toprotect the silicon-containing surface under the stack from oxidizing.The formation of the RuSi_(x)O_(y)-containing adhesion layer enhancesthe oxidation-resistance properties of the stack. One of ordinary skillin the art will recognize that the first electrode 56 includes one ormore RuSi_(x)O_(y)-containing adhesion layers and one or more additionalconductive layers, as described with reference to FIG. 5.

[0051] The RuSi_(x)O_(y)-containing adhesion layers of the presentinvention have numerous and varied applications in the area ofsemiconductor device and semiconductor structure fabrication. Forexample, the use of RuSi_(x)O_(y)-containing adhesion layers of thepresent invention is described with reference to FIG. 7, wherein acontact liner requiring adhesion and oxidation barrier characteristicsis described. More specifically, device structure 70 is fabricated inaccordance with conventional processing techniques through the formationof contact opening 102 prior to metallization of the contact area 94 ofsubstrate 80. As such, prior to metallization, the device structure 70includes field oxide regions 82 and active areas (represented by regionsof substrate 80 not covered by field oxide). Word line 92 and fieldeffect transistors (FET) 90 are formed relative to the field oxideregions 82 in the active areas. Suitably doped source/drain regions 84,86 are formed by conventional methods known to one of ordinary skill inthe art. A conformal layer of oxide material 88 is formed thereover andcontact opening 102 is defined therein to the contact area 94 of dopedsource region 84 of substrate 80. Thereafter, one or more metallizationor conductive layers (e.g., titanium nitride) are formed in the contactopening 102 for providing electrical connection to doped source/drainregions 84. Preferably, contact liner 100 is a RuSi_(x)O_(y)-containingadhesion layer formed according to the present invention on bottomsurface 96 and the one or more side walls 98 defining the contactopening 102. The RuSi_(x)O_(y)-containing adhesion layer is generallydeposited over the entire substrate assembly and then planarized to formthe contact liner 100. Thereafter, a conductive material 104 (e.g.,aluminum, W, Cu) is formed in the contact opening for providingconnection to doped source/drain regions 84 of substrate 80.

[0052] Alternatively, the present invention may be used to fabricate abottom electrode of a high dielectric capacitor of a storage cell thatincludes one or more RuSi_(x)O_(y)-containing adhesion layers, as shownin FIG. 8. Specifically, a device structure 106 is fabricated inaccordance with conventional processing techniques through the formationof an opening 114 prior to depositing a bottom electrode structure 118on the surface 112 (preferably a silicon-containing surface) and surface116 defining the opening 114. A bottom electrode structure 118, whichincludes a RuSi_(x)O_(y)-containing adhesion layer and one or more otherconductive layers is formed in opening 114 according to the presentinvention, as previously described herein. The substrate assembly 110may include various elements, such as field oxide regions, activeregions (i.e., regions of a silicon substrate not covered by fieldoxide), word lines, field effect transistors (FET), and source/drainregions created in the silicon substrate. An insulative layer of oxidematerial 113 is formed over the substrate assembly 110. The opening 114in the insulative layer of oxide material 113 is a small, high aspectratio opening. As described herein, small, high aspect ratio openingshave feature sizes or critical dimensions below about 1 micron (e.g.,such as a diameter or width of an opening being less than about 1micron) and aspect ratios (ratio of depth to width) greater than about4. Such aspect ratios are applicable to contact holes, vias, trenches,and any other configured openings. For example, a trench having anopening of 1 micron and depth of 3 microns has an aspect ratio of 3. Thepresent invention is particularly useful in the formation of adhesionlayers in small, high aspect ratio features due to the use of CVDprocesses for forming conformal RuSi_(x)O_(y)-containing adhesion layersover step structures.

[0053] As shown in FIG. 8, a bottom electrode structure 118, including aRuSi_(x)O_(y)-containing adhesion layer, is formed on the surface 112and the one or more surfaces 116 defining opening 114. In thisparticular embodiment of the invention, the electrode stack layers areformed over the entire structure, including the surface 112 and surfaces116. The layers are then formed into bottom electrode structure 118. Byway of example, the stack layers may be etched or planarized to removedesired regions for forming the bottom electrode structure 118.Thereafter, dielectric layer 120 is formed relative to the bottomelectrode structure 118. The second electrode 192 is then formedrelative to the dielectric material 120. Such an electrode may, forexample, be composed of any suitable conductive material, such astungsten nitride, titanium nitride, tantalum nitride, ruthenium,rhodium, iridium, ruthenium oxide, iridium oxide, any combinationthereof, or any other conductive material typically used as an electrodeor electrode layer of a storage cell capacitor. In accordance with theinstant embodiment of the present invention, the bottom electrode isconformally formed of a stack of layers, including aRuSi_(x)O_(y)-containing adhesion layer, having uniform thickness anddeposited using CVD processes to provide suitable oxidation-resistantadhesive properties.

[0054] It will be recognized by one skilled in the art that, in additionto the embodiments described herein, any capacitor formed relative to asurface (e.g., silicon-containing surface) whereupon adhesion andoxidation barrier properties are required, and/or conformally formed,conductive layers are required, may benefit from the present invention.For example, container capacitors typically include electrodes formed onsurfaces requiring conformal formation of a bottom electrode. Such acontainer capacitor storage cell is described in U.S. Pat. No. 5,270,241to Dennison, et al., entitled “Optimized Container Stack Capacitor DRAMCell Utilizing Sacrificial Oxide Deposition and Chemical MechanicalPolishing,” issued Dec. 14, 1993, and incorporated herein by thisreference. The present invention may also be employed in the fabricationof other semiconductor processes and structures for various devices(e.g., CMOS devices, memory devices, logic devices, etc.). It should beunderstood that the present invention is not limited to the illustrativeembodiments described herein and that the RuSi_(x)O_(y)-containingadhesion layer of the present invention may be used for any applicationrequiring adhesion and oxidation barrier characteristics, particularlythose for preventing diffusion of silicon and/or oxygen into adjacentlayers.

[0055] A RuSi_(x)O_(y) adhesion layer was formed by a conventional CVDprocess. The reaction chamber used for fabricating the sample wafer wasa CVD chamber manufactured by Plasma Quest (Dallas, Tex.) and thebubblers used are glass research bubblers from Technical Glass Service(Boise, Id.). The conditions used for forming theRuSi_(x)O_(y)-containing adhesion layer include:

[0056] Ruthenium Precursor: C₆H₈Ru(CO)₃.

[0057] Ruthenium Carrier Gas for use through Bubbler: 50 sccm of helium.

[0058] Ruthenium Bubbler Conditions: pressure of 3 torr, temperature of25° C.

[0059] Reaction Chamber Conditions: pressure of 0.5 torr, depositiontemperature of 305° C. at wafer surface, 5 sccm SiH₄.

[0060] Deposition Time: 0.5 minute.

[0061] The conditions used for the forming the ruthenium oxide layerinclude:

[0062] Ruthenium Precursor: C₆H₈Ru(CO)₃.

[0063] Ruthenium Carrier Gas for use through Bubbler: 50 sccm of helium.

[0064] Ruthenium Bubbler Conditions: pressure of 3 torr, temperature of25° C.

[0065] Reaction Chamber Conditions: pressure of 3 torr, depositiontemperature of 230° C. at wafer surface.

[0066] Deposition Time: 3 minutes.

[0067] It will be recognized by a person having skill in the art that,in addition to the embodiments described herein, the present inventionmay be carried out to include controlled deposition of one or more“monolayers” of RuSi_(x)O_(y)-containing adhesion layer(s). Thisprocess, typically referred to as atomic layer deposition, atomic layerepitaxy, sequential layer deposition, or pulsed-gas CVD, involves use ofa precursor based on self-limiting surface reactions. Generally, asubstrate is exposed to a first species that deposits as a monolayer andthe monolayer then being exposed to a second species to form a fullyreacted layer plus gaseous byproducts. The process is typically repeateduntil a desired thickness is achieved. Atomic layer deposition andvarious methods to carry out the same are described in U.S. Pat. No.4,058,430 to Suntola et al., entitled “Method for Producing CompoundThin Films,” U.S. Pat. No. 4,413,022 to Suntola et al., entitled “Methodfor Performing Growth of Compound Thin Films,” Ylilammi, “MonolayerThickness in Atomic Layer Deposition,” Thin Solid Films 279 (1996)124-130, and S. M. George et al., “Surface Chemistry for Atomic LayerGrowth,” J. Phys. Chem. 1996, 100, 13121-13131, the disclosures of eachsuch document are hereby incorporated by reference.

[0068] The process has also been described as a CVD operation performedunder controlled conditions which cause the deposition to beself-limiting to yield deposition of, at most, a monolayer. Thedeposition of a monolayer is significant in many areas because itfacilitates theoretically conformal films, precise control of filmthickness, and improved compound material layer uniformity. In practice,however, the deposited “monolayer” is rarely a complete and truemonolayer, there always being something less than complete coverage ofan underlying layer or other surface due to the space consumed by thenon-incorporating components of the metal organic precursor.Combinations of deposition processes discussed herein may be used toprovide deposition materials (e.g., Atomic Layer Deposition (ALD) andnon-ALD types of CVD). Accordingly, exemplary embodiments of theinvention include within their scope deposition of a monolayer underconditions designed to achieve such results, as well as conditions witha subsequent shift of conditions toward the CVD regime, such that, tothe extent required, the deposition of the RuSi_(x)O_(y)-containingadhesion layers is effected as 3-5 “monolayers” rather than a singlemonolayer.

[0069] More specifically, deposition of monolayers is accomplished in aCVD chamber, as previously described with reference to the CVDdeposition method, but with the addition of pulsing valves to allow theswitching between the precursor and purge gas and the SiH₄(Si₂H₆) andpurge gas. Bubblers, however, are not required since carrier gases mayor may not be used, depending on the configuration of the vacuum system.For this example, a simple storage ampule with a single outlet and noinlet is used. As with the CVD method, C₆H₈Ru(CO)₃ is used as theruthenium precursor. The deposition temperature of the wafer surface is50-250 degrees C. and the reaction chamber is kept at a variablepressure range of about 0.5 torr to about 0.0001 torr. The reactionchamber is fully opened to the pumps of the vacuum system to create avacuum in the CVD chamber and the ruthenium precursor gas is introducedat low pressure, preferably about 0.0001 torr. Introduction of theruthenium precursor gas under these conditions will result in thedeposition of, at most, a monolayer of ruthenium over the surface of thewafer. A purge cycle is then initiated by introducing a nonreactive gas,such as He or Ar, at a volumetric flow rate of about 50 sccm into thereaction chamber at 0.5 torr. It is understood that any suitablenonreactive gas may be used and that the nonreactive gas may beintroduced at a rate of between about 0.1 sccm to about 500 sccm tooptimize system conditions. Silane or disilane is introduced into thereaction chamber at a rate of about 5 sccm, which results in thedeposition of a silicon monolayer over the previously depositedruthenium monolayer. This is followed by a purge cycle of nonreactivegas, as previously described. It is understood that oxygen can be addedas a separate oxygen/purge cycle as needed for every individual cycle inorder to give the required oxygen content. In general, however,sufficient oxygen is available from background O₂ and H₂O in the chamberto oxidize the underlying RuSi_(x) layer formed in the preceding steps.The monolayer of adsorbed precursor from the initial precursordeposition step will react directly when exposed to the reaction gas inthe third step of the foregoing dose precursor/ purge/ dose reactiongas/ purge sequence, which results in controlled deposition of one ormore RuSi_(x)O_(y)-containing adhesion monolayers.

[0070] Although this invention has been described with reference toillustrative embodiments, it is not meant to be construed in a limitingsense. As described previously, one skilled in the art will recognizethat various other illustrative applications may use theRuSi_(x)O_(y)-containing adhesion layer as described herein to takeadvantage of the beneficial adhesion and oxidation resistancecharacteristics thereof. Various modifications of the illustrativeembodiments, as well as additional embodiments to the invention, will beapparent to persons skilled in the art upon reference to thisdescription. It is therefore contemplated that any such modifications orembodiments may fall within the scope of the present invention asdefined by the accompanying claims.

What is claimed is:
 1. A method for forming a semiconductor devicestructure having a RuSi_(x)O_(y) adhesion layer, the method comprising:(a) placing a semiconductor substrate assembly in a reaction chamber,said semiconductor substrate assembly having a surface; (b) introducinga ruthenium precursor into said reaction chamber to form a single layerof ruthenium on at least a portion of said semiconductor substratesurface; (c) introducing a non-reactive gas into said reaction chamberto substantially cover said single layer of ruthenium and purge saidruthenium precursor from said reaction chamber; (d) introducing asilicon precursor into said reaction chamber to form a single layer ofRuSi_(x)O_(y) on at least a portion of said semiconductor substratesurface; and (e) introducing a non-reactive gas into said reactionchamber to substantially cover said single layer of RuSi_(x)O_(y) andpurge said silicon precursor from said reaction chamber.
 2. The methodof claim 1, further comprising introducing an oxygen-containingsubstance into said reaction chamber to form a single adhesion layer ofRuSi_(x)O_(y) on at least a portion of said semiconductor substratesurface.
 3. The method of claim 1, wherein introducing a siliconprecursor into said reaction chamber comprises introducing a siliconprecursor in an oxidizing atmosphere within said reaction chamber. 4.The method of claim 3, wherein introducing a silicon precursor in anoxidizing atmosphere comprises introducing said silicon precursor in anatmosphere comprising air, oxygen, or an oxygen-containing compound. 5.The method of claim 1, wherein introducing said ruthenium precursorcomprises introducing C₆H₈Ru(CO)₃.
 6. The method of claim 1, whereinintroducing a non-reactive gas comprises introducing a non-reactive gasselected from the group consisting of nitrogen, argon, neon, helium, andxenon.
 7. The method of claim 1, wherein introducing a silicon precursorcomprises introducing silane or disilane into said reaction chamber. 8.The method of claim 1, wherein steps (a) through (e) are repeated toform 3 to 5 RuSi_(x)O_(y) adhesion monolayers.
 9. A method for forming asemiconductor device structure having a RuSi_(x)O_(y) adhesion layer,the method comprising: (a) placing a semiconductor substrate assembly ina reaction chamber, said semiconductor substrate assembly having asurface; (b) introducing C₆H₈Ru(CO)₃ into said reaction chamber to forma single layer of ruthenium on at least a portion of said semiconductorsubstrate surface; (c) introducing a non-reactive gas into said reactionchamber to substantially cover said single layer of ruthenium and purgesaid C₆H₈Ru(CO)₃ from said reaction chamber; (d) introducing a siliconprecursor into said reaction chamber to form a single layer ofRuSi_(x)O_(y) on at least a portion of said semiconductor substratesurface; and (e) introducing a non-reactive gas into said reactionchamber to substantially cover said single layer of RuSi_(x)O_(y) andpurge said silicon precursor from said reaction chamber.
 10. The methodof claim 9, further comprising introducing an oxygen-containingsubstance into said reaction chamber to form a single adhesion layer ofRuSi_(x)O_(y) on at least a portion of said semiconductor substratesurface.
 11. The method of claim 9, wherein introducing a siliconprecursor into said reaction chamber comprises introducing a siliconprecursor in an oxidizing atmosphere within said reaction chamber. 12.The method of claim 11, wherein introducing a silicon precursor in anoxidizing atmosphere comprises introducing said silicon precursor in anatmosphere comprising air, oxygen, or an oxygen-containing compound. 13.The method of claim 9, wherein introducing a non-reactive gas comprisesintroducing a non-reactive gas selected from the group consisting ofnitrogen, argon, neon, helium, and xenon.
 14. The method of claim 9,wherein introducing a silicon precursor comprises introducing silane ordisilane into said reaction chamber.
 15. The method of claim 9, whereinsteps (a) through (e) are repeated to form 3 to 5 RuSi_(x)O_(y) adhesionmonolayers.
 16. A method for forming a semiconductor device structurehaving a RuSi_(x)O_(y) adhesion layer, the method comprising: (a)placing a semiconductor substrate assembly in a reaction chamber, saidsemiconductor substrate assembly having a surface; (b) introducingC₇H₁₀Ru(CO)₃ into said reaction chamber to form a single layer ofruthenium on at least a portion of said semiconductor substrate surface;(c) introducing a non-reactive gas into said reaction chamber tosubstantially cover said single layer of ruthenium and purge saidC₇H₁₀Ru(CO)₃ from said reaction chamber; (d) introducing a siliconprecursor into said reaction chamber to form a single layer ofRuSi_(x)O_(y) on at least a portion of said semiconductor substratesurface; and (e) introducing a non-reactive gas into said reactionchamber to substantially cover said single layer of RuSi_(x)O_(y) andpurge said silicon precursor from said reaction chamber.
 17. The methodof claim 16, further comprising introducing an oxygen-containingsubstance into said reaction chamber to form a single adhesion layer ofRuSi_(x)O_(y) on at least a portion of said semiconductor substratesurface.
 18. The method of claim 16, wherein introducing a siliconprecursor into said reaction chamber comprises introducing a siliconprecursor in an oxidizing atmosphere within said reaction chamber. 19.The method of claim 18, wherein introducing a silicon precursor in anoxidizing atmosphere comprises introducing said silicon precursor in anatmosphere comprising air, oxygen, or an oxygen-containing compound. 20.The method of claim 16, wherein introducing a non-reactive gas comprisesintroducing a non-reactive gas selected from the group consisting ofnitrogen, argon, neon, helium, and xenon.
 21. The method of claim 16,wherein introducing a silicon precursor comprises introducing silane ordisilane into said reaction chamber.
 22. The method of claim 16, whereinsteps (a) through (e) are repeated to form 3 to 5 RuSi_(x)O_(y) adhesionmonolayers.
 23. A method for forming a semiconductor device structurehaving a RuSi_(x)O_(y) adhesion layer, the method comprising: (a)placing a semiconductor substrate assembly in a reaction chamber, saidsemiconductor substrate assembly having a surface; (b) introducing aruthenium precursor into said reaction chamber to form a single layer ofruthenium on at least a portion of said semiconductor substrate surface;(c) introducing a non-reactive gas into said reaction chamber tosubstantially cover said single layer of ruthenium and purge saidruthenium precursor from said reaction chamber; (d) introducing asilicon precursor and an oxygen-containing substance into said reactionchamber to form a single layer of RuSi_(x)O_(y) on at least a portion ofsaid semiconductor substrate surface; and (e) introducing a non-reactivegas into said reaction chamber to substantially cover said single layerof RuSi_(x)O_(y) and purge said silicon precursor from said reactionchamber.
 24. The method of claim 23, wherein introducing a siliconprecursor and an oxygen-containing substance comprises introducing saidsilicon precursor in an atmosphere comprising air, oxygen, or anoxygen-containing compound.
 25. The method of claim 23, whereinintroducing said ruthenium precursor comprises introducing C₆H₈Ru(CO)₃or C₇H₁₀Ru(CO)₃.
 26. The method of claim 23, wherein introducing anon-reactive gas comprises introducing a non-reactive gas selected fromthe group consisting of nitrogen, argon, neon, helium, and xenon. 27.The method of claim 23, wherein introducing a silicon precursorcomprises introducing silane or disilane into said reaction chamber. 28.The method of claim 23, wherein steps (a) through (e) are repeated toform 3 to 5 RuSi_(x)O_(y) adhesion monolayers.